Does LR Raise Serum Lactate Compared to NS?
October 1, 2018
Update on Friday’s Post
Hey all, you may want to look at Friday’s post on epi vs norepi for cardiogenic shock after acute MI. There may be a confounder we hadn’t previously considered. I have made an addendum to the post. Be sure to read that and the comments. Thanks, Scott, for the real-time feedback – one of the benefits of #FOAMed.
Written by Thomas Davis
A rapid infusion of lactated Ringer’s increased serum lactate but did not raise the serum lactate more so than compared to normal saline.
Why does this matter?
The Centers for Medicare and Medicaid Services have trained us like one of Pavlov’s dogs: lactic acidosis must be due to sepsis. However, many other causes of lactatemia exist. For example, epinephrine, albuterol, anti-retrovirals, metformin, propofol, and alcohols have all been shown to increase lactate. Although it seems certain that infusing lactated Ringer’s (LR) must increase serum lactate, a prior study suggests that may not be the case. In that study, 1 liter of LR was given over 1 hour. What if LR is given at higher doses and more quickly, as prescribed for septic shock?
Lactate in, lactate out
This was a double-blind RCT that administered 30cc/kg of lactated Ringer’s or normal saline (NS) via pressure bag to 30 healthy volunteers. Average fluid bolus duration was 47 minutes. Lactate was measured immediately before and 5 minutes after IV fluid bolus. In the LR group, lactate increased by 0.93 mmol/L (p = 0.003). However, compared to NS, which increased by 0.37 mmol/L, there was no statistical difference between the two groups (p = 0.2). This study shows that infusing lactate in the right arm will increase the amount of lactate drawn out of the left arm. Unfortunately, it does not answer what happens in septic patients as their bodies metabolize the infused lactate. What this study does do is remind us that a persistently elevated lactate does not always indicate the need for more fluid. After all, not all lactic acidosis is due to shock.
Does Intravenous Lactated Ringer’s Solution Raise Serum Lactate? J Emerg Med. 2018 Sep;55(3):313-318. doi: 10.1016/j.jemermed.2018.05.031. Epub 2018 Jul 20.
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Reviewed by Clay Smith